The present invention relates to a power supply device and a semiconductor device for use therein and, particularly, to a power supply device having a power factor correction circuit.
Power supply devices for use in servers, home appliances, etc. have a problem in which reactive power is generated due to a difference between input voltage and input current waveforms, when converting alternate current (AC) to direct current (DC). Another problem concerned is that such a difference between the waveforms of an input voltage and an input current gives rise to a harmonic current that becomes noise having effect on other electrical equipment and the like. As a countermeasure against this problem, power factor correction (PFC) is performed that shapes the waveform of an input current into a phase and waveform equivalent to those of an input voltage.
Examples of power factor correction circuits are described in Japanese Unexamined Patent Publication No. Hei 10(1998)-174428 (Patent Document 1), Japanese Unexamined Patent Publication No. 2009-261042 (Patent Document 2), and Japanese Unexamined Patent Publication No. 2007-195282 (Patent Document 3).